While a poor solution for programming or word processing where input speed is vital, very useful for music, photo and video processing as they are reliant on contextual functions and emulating real-world interfaces.

You could possibly make it quite good for spreadsheets as they're somewhere in the middle between data input (where touchscreen as an input method is slower and frustrating) and function selection/formatting (where, depending on the context of what you're doing, all of the functions you require are suddenly at your fingertips rather than buried somewhere on a ribbon or sub menu).